Crown prosecutor Susan Hedge said Blair had supplied a heroin substitute to a young girl in order to get the drugs to her son, Simeon Frederick George Blair, who was found guilty last year of murdering Cleveland Paul Clay during a fight at Maryborough's Carlton Hotel.

Ms Hedge said Blair had supplied the girl with drugs on four occasions.

The girl then attended the prison and gave the drugs to Blair's son.

The court heard Blair had received $300 for supplying the drugs, in addition to money she was given to purchase the drugs.

She was told she would receive more money after some of the drugs were sold.

The court heard the girl texted Blair after delivering the drugs to the prison, reassuring her that it "all went fine".

Blair responded, telling the girl her son sounded "very happy".

"It's party time for them now," Blair told the girl.

Defence barrister Paul Rutledge said Blair had become involved because of her son.